The present invention relates to a polarization-sensitive optical measurement instrument.
In recent years, optical coherence tomography (OCT) by which light is used for acquiring images reflecting the surface structure and the internal structure of the object of measurement is attracting note (Medical Photonics No. 1 (2010), pp. 29-33 (Non-patent document 1) and Medical Photonics No. 7 (2011), pp. 58-64 (Non-patent document 2)). OCT, as it is non-invasive to human bodies, is expected to be safely applicable to medical and biological purposes. In the ophthalmologic field, in particular, apparatuses for forming images of eye ground and cornea among others are already in the stage of practical use.
A living tissue may sometimes be birefringent. For instance, the crystalline lens of a human eyeball has a laminar structure formed of a plurality of layers, differing in birefringent direction from one another, one stacked over another. However, as these layers are the same in refractive index, conventional OCT, by which the refractive index of the living tissue is measured, cannot visualize their structure. As a technique to visualize such a structure, polarization-sensitive OCT has been developed (Japanese Unexamined Patent Application Publication No. 2004-28970 (Patent document 1)).